1. Field of the Invention
The present invention relates to a magnetic medium for magnetic embossment (characters in relief) and a magnetic card using the same, which are employed for identification, credit, cashless systems, POS etc.
2. Description of the Prior Art
Conventional embossed cards are such that the name of an owner (user), owner No., publication No., account No., the term of validity, etc. in the form of embossment characters visible to the eye are embossed on the basis of a predetermined format at a part or predetermined position of the card. When the card is used, a chit or slip is imprinted with the characters by the use of carbon or non-carbon paper by means of an imprinter at a dealer so as to draw up a document as visible evidence of transaction containing the visible characters or patterns, whereby the cards serve the conveniences of monetary facilites, POS users or the card users.
As regards the aforementioned embossed cards, however, the illicit uses of the cards based on forgery, falsification etc. are increasing because (1) a hard polyvinyl chloride sheet, which is commercially available, is used as a substrate material, and (2) embossors (devices for embossment) are also widespread.
As expedients for solving such problems, forgery preventive techniques based on magnetic embossment as disclosed in the official gazette of Japanese Patent Application Laid-Open No. 57-117129, the official gazette of Japanese Patent Application Publication No. 54-11107, etc. have been developed.
The method in the official gazette of Japanese Patent Application Laid-Open No. 57-117129, however, employes a thick magnetic layer having a thickness of 0.4-0.5 mm, so that in case of applying it to, for example, any of cards having total thicknesses of 0.7-0.8 mm now in use, a recess needs to be provided in a center core or the like beforehand, which has led to a high cost in production. Further, no means for concealing the color tone of the magnetic layer is provided, so that even when color layers are formed on the front and rear sides of the strip of the magnetic layer which is elongate by way of example, the ranges of choice of the color tones of the color layers have been limited (when the color layer is thin in a light color or bright color, the color of the main magnetic layer remains visible). Moreover, since the magnetic layer is as thick as 0.4-0.5 mm, this magnetic layer portion cannot be used as a signal recording portion which is formed by a conventional magnetic recording system. Furthermore, since the prior-art magnetic-embossment magnetic medium has only the magnetic layer of high coercive force exhibiting a low permeability, it is difficult to endow the medium with a function for checking forgery, alteration etc.
On the other hand, a device for reading magnetic cards disclosed in the official gazette of Japanese Patent Application Publication No. 54-11107 uses a card similar to that disclosed in the official gazette of Japanese Patent Application Laid-Open No. 57-117129 and it reads the embossment characters of the magnetic card which have been formed by developing magnetization owing to the reverse effect of magnetostriction. This measure is not satisfactory for checking forgery and alteration, and the effect of preventing the forgery and alteration is insufficient. It is also impossible to employ the conventional magnetic recording system.
An object of the present invention is to provide a magnetic medium for magnetic embossment and a magnetic card which can eliminate the problems of the prior art as stated above.